Method of electric arc welding



April so', 1929., @y mmm www METHOD@ ELECTRIG ARC WELDING Filed Sepia. 19y 1918 Ff@ z Patented Apr. so, 1929.

UNITED STATES PAT JOHN C. LINCOLN, 0F EAST CLEVELAND, OHIO.

METHOD or Ennemi@ Anc WELDING.

Application filed September My invention relates to improvements in methods lof welding, and'has for its object the production of welds which will be ductile, as strong or stronger-than the metal welded, economical in the cost of labor and current, as well as preferably avoiding the preparation of the surfaces or edges to be welded.

-The typical welding operation of my 1nvention proceeds under conditions of excluding any' large component of air or -oxygen from access to the molten metal 'during the welding operation and effectively directing the electric arc, controlling its action and observing the progress of the Welding operation so that the arc may be advanced as required. i

The control of the electric are preferably is effected by means of a magnetic eld, While the best welding conditions are secured by partially or effectively excluding the air from the are and the metal while in molten condition, through the agency of an inert gaseous medium, forming a coveringr envelope therefor. This gaseous medium may be produced by the arc itself on a supply of such gaseous medium, such as lcarbcm-dioxide or nitrogen, may be maintained during welding operations.

llt is well known that fairly satisfactory welds can be made upon steel plates by means of the Oxy-acetylene flame or the electric arc. The principal objection to the work hitherto produced by either of these means is that the welds are lacking in the necessary ductility, while another objection is found in that said welds are not as strong as the metal plates thus united. l

Moreover, an important item involving both expense and delay, has been present in the` necessity forv preparing the metal for welding. This preparation of sheet metal ordinarily has consisted in beveling the edges of the sheets of metal to be Welded, so that the opposing or the substantially abutting surfaces would exhibit an angle approximately of 90, in order to enable the electric arc to reach the bottom of the space thus afforded for the weld. It has been my purpose therefore, to devise a method for welding sheet metal and other metallic members, without any previous preparation of the edges thereof.

, During my experiments, I have ascertained that aprime factor in obtaining ductility in a weld is the avoidance as far as commercially possible, of any oxidizing action ofthe air,

19, 1918. Serial No. 254,773.

which may be excluded by means of a gaseous medium, either under cover or in the open. In addition, it is essential to observe the progress of the welding operation, and highly desirable that the arc Within its inert gaseous envelope, shall be steadied and directed by a concentric magnetic field.

For this purpose, I have devised a simple, portable device wherein the arc-forming electrode may be inserted and observed during its welding action, which device substantially excludes the atmospheric air, and being of small size, the oxygen initially contained therein almostimmediately is consumed, so that the device contains only the inert nitrogen and products of the welding operation, such as iron vapor. The inert gas, however, may be supplied to the effective portion of an electric arc in the open, by suitable external means, such as from a cylinder of liquelicd carbon-dioxide equipped with reducing and controlling valves, together with a pipe extending to the proximity of the arc.

To insure the steadying and directing magnetic field for the arc, there is provided an en closing solenoid winding in substantially the plane of the are, while an inductive resistance is interposed in the arc-forming circuit. Great difficulty has been experienced hitherto in the practice of arc-welding, particularly with the carbon electrode, by reason of the fact that the arc tends to jump from the material to be welded through the path of least resistance. The resistance of the path or the resistance of the arc is affected by the amount of vapor generated from the material being welded, and there is a tendency commonly observable for the arc to progress, jumping from point to point, instead of a substantially steady progress necessary-to produce a uni-v form weld.

This irregular jumping tendency is due, no doubt, to the assumed fact that the arc tends to persist in a given spot because more vapor is thrown into the are from the molten metal beneath the are, than can be thrown into the are from the cooler adjacent metal. Thus, the normal tendency of the arc is to persist in the spot which is already heated until the arc lengthens to such an extent that a lower resistance is encountered beneath a traveling carbon electrode, than is encountered by the persisting arc. from the former to the new position, simply to repeat the process, as the electrode is advanced along the weld. As a result, the weld,

The arc, accordingly, jumps recting the arc during welding operations.

The prime factor thereof is a magnetic field of force in which the lines are substantially parallel to the desired direction of current flow in the arc, whereby said arc is focused and stabilized in its action.

It is well recognized that an electric are in the presence of a magnetic field, tends to be deflected laterally with reference to the direction of the arc, and the direction of the magnetic lines of such field. However, if the direction of the magnetic lines is parallel to the direction of the arc, the magnetic iield will exert no appreciable eiect upon the arc. This being the case, it is clear that the magnetic lines passingfrom the material to be welded back to themagnet, will tend to blow out any component of the arc not in line with the axis of the electrode, and also will tendto make the arc itself more nearly a cylinder thanl a cone, as is normally the case. With this action, however, there is coupled the greater liability of blowing out the arc, and

preferably the circuit is so arranged as to offset this.

this energy will be released at the arc in the guise of a momentary increase involtage before the circuit canbe broken. It is possible to desi n this inductive resistance so that any desire momentary increase of voltage is provided at the arc, necessaryto make it substantially stable. For example, with a voltage of fifty-five volts in the external circuit and approximately forty volts across the arc, the loss in the solenoid winding or ohmic portion of the inductive resistancel would be fifteen volts. By proper design of the inductive resistance, 1n a' manner Well known to those skilled in the art, the welding arc may be made as stable as it wouldbe with a current of from one hundred to one hundredA fifty volts provided aci-ossia non-inductive resistance. l'

By employing the method or methods above outlined, riveting may be avoided, and

much of the Work upon steel bridges, steel hulls for vessels, boilers, and the'like may be performed with material gain of time and at a very much lower cost than is possible with riveting. In addition, the weld may be made stronger than the original metal welded, while the riveted joint has a strength at best of fromv to 85% of that of the members l l' thus united.

An advantage of distinct practical importance in arc-welding in accordance with the improvements here disclosed, is that the arc always is enclosed within a protective chamber, which shields the eyes of the operative andV other by-standers from the intense rays of light resulting therefrom. The operative thus is able to dispense with the usual dark glass helmet and may observe the welding operation with equal facility, Wh e able as well, to give casual attention to his surroundings. 1

The method herein described and explained in connection withsimple means for practicing the same, obviously is not vlimited in its practice. to the means set forth, nor to the exact details of procedure which are herein outlined. I may refer to the accompanying drawings, further to explain my improvements,.wherein:- I

Fig. 1 is a cross-sectional view of apparatus, including a protective chamber and means for viewing the arc, adapted for prac-4 ticing the method or methods of my invention.

Figs. 2 and 3, respectively, are fragmentary views of sheet metal plates, partially and completely welded in accordance with my invention.

Figs. 4 and 5 are similar fragmentary views of sheet metal plates designed for welding in accordance with further improvements of my invention.

Fig. 6 is a view, partially diagrammatic in character, by which I have' endeavored to show the action of welding as controlled by the magnetic field, and

Fig. 7 is a diagram illustrating the apparatus used.

Throughout the several figures, I have employed the same character of reference to indicate similar parts or members.

A simple type of apparatusl for practicing my invention, is shown in the drawings. This comprises vessentially a hand-controlled closed chamber for the arc and molten metal adapted to exclude. the air therefrom, with which are associated a solenoid winding and means for viewing the action of the arc.

vThe flat base-plate a is constructed from copper, upon'which are mounted the vulcabeston insulation b', (compressed and lvulcanizedasbestos fiber), the annular core c and 'exciting winding 'bof the stabilizing electromagnet. lAn upper copper plate d has a handle d at one side, and the-vision appliance e positioned' at an angle above the opening into the central rotective chamber a. This chamber preferably is of restricted volume inorder to .limit the amount of air initiallyl present therein and to retain in quiescent state, the resultant rotective gaseous envelope. It desired, a tu e f, shown in dotted lines, may also communicate with said chamber, for introducing a' limited, continuous or regulated supply of inert gas, sufficient to drive out or exclude the air completely. Ordinarily, this is not necessary, however.

As a mechanical means for further excluding the air, the plate a is equipped along its bottom yface with sets of peripheral springtlngers g bearing upon a flexible continuous packing of asbestos cloth h which is pressed closely against the surface of the sheet metal members z' y' undergoing the welding opera.- tion. In addition, the electrode c is closely litted within the thimble 7c', substantially to shut E the entrance'of air. The electrode lc, which forms the negative terminal of the arc, maybe of carbon or metal and of an alloy such as will give the desired characteristics to the weld. Said electrode 7c is equipped with a handle Z, by which it may be manipulated by the operative during the welding operations or controlled in any other suitable manner. It is necessary only, that the electrode shall at all times be in View of and under the control of the operative for directing and regulating the welding action of the arc. ln order properlyfto accomplish this, the vision appliance is equipped with a dark glass e', with outer radiator-plates ez'to dissipate the heat and with interior deposit ledges e for catching the small amount of oxide formed during the welding operation and preventing its filming over the underside of the glass. Thus the action of the are may be constantly observed and regulated by the operative.

This vsimple welding device is assumed to be progressively moved away from the observer, in the direction or along the line of the opposing edges of the sheet metal plates z" y', shown in Fig. 1, as the welding operation proceeds.

These plates may merely be placed in substantial abutment. as also shown in fragmentary form Fig. 2, or they may be somewhat separated as in Fig. 4, while optionally,a flat wire or welding strip of alloy i', such as nickel-steel, manganese-steel andy the like, may be placed upon or interposed therebetween to form part of the welded seam.

In the diagram, Fig. 7, the generator G is shown connected throu 'h the inductive resistance R with the wel in are 7c, z', and also with the magnet windings adapted for stabilizin the arc.

Pre erably the plates i j need. not be specially prepared for welding7 but are disposed with their edges in abutment, or in opposition to each other. The arc. is then struck and progressively advanced along the .seam as rapidly as the welding is accomplished. A weld, either slightly in excess of one-half the thickness ofthe plates or sheets, may thus be perfected as in Fig. 2, or it may proceed the entire thickness thereof, with the use of a backing or bridgin strip j as in Fi 1,.

which stripaccordi'ng y becomes a part o the welded seam as the 4arc reaches and fuses its exposed section. To complete the weld of Fig. 2, the arc is then .progressively applied to the opposite sides of the sheets which are thus fused or welded into a seam formed of intersecting welds, each slightly in excess of one-half the thickness of the sheets, as shown in Fig. 3. Any losses or" metal or added metal may be supplied by the wire or strip i', as desired. If a welding strip is employed either oi steel or alloy, or if alloy electrode is'used, of course these metals will contribute to the body and characteristics of the welded seam.

ln Fig. 6, l have endeavored somewhat diagrammat-ieally to show the actionof the we1ding arc in forming the partial seam z' of Fig. 2 in accordance with my invention. The electrode in is pictured with the arc drawn from the steel y', and in the process of welding, there results a marked depression m', whichpresumably is due to the boiling out of the molten metal under the heat ofthe electric arc. The progress of the arc is assumed to be from right to left. Therefore, as the welding proceeds, the metall is melted from the leitside of the depression under the intense action of the arc, and actually transferred' to the right side thereof, where it is soli died. A somewhat violent agitation of the molten metal takes place beneath the arc, so that with the addition of any alloying material, a fairly uniform, ductile alloyed seam results.

lt will be recognized that any contained air within the chamber d will be exhausted of its oxygen content almost immediately and with careful use of the welding device, only a negligible quantity of air thereafter will find entrance to said chamber'. Consequently, the welding operation takes place in an atmosphere of nitrogen with some generated iron vapors, and also carbon monoxide and carbon dioxide when the carbon electrode is used, hence no oxidizing action can take place and the weld is clean and ductile.

Should the surface be rough or slightl unn even, of course the mechanical means s own will not exclude the air as effectively as above recited. ln these circumstances, an external supply of an inert gas, as from a cylinder of Acarbon-dioxide, may with advantage be inconverge somewhat or render more truly i cylindrical, the normally frus-to-conical shape of the arc, and by their concentric directive effect, materially stabilize the welding action of the electric arc, while the continuity of such arc is contributed to by the inductance vR, as already explained` This concentric annular magnetic' ield, as will be'better appreciated by considering Fig. 1, is strongest in the region of the side walls of the opening through the base plate a and is weakest in the center, or-the axis of the electrode 7:. Such magnetic ield thus has a directive component at right an les to every direction of current-How in t e arc, except to the one desired, as opposed tothe dispersive action of a field intensified in the axis of the arc.

This method of welding, wherein the electric arc is enclosed within a magnetic field and the arc and molten metal within a relatively quiescent envelope of inert gas, may be more rapidly and economically practiced4 than can any methodknown to the art.

Having now described the preferred method of practicing my invention, I claim v as new and desire to secure by Letters Patent I the following 1. The method of arc-welding, which consists.in placing an` air-,excluding member over the Work, striking an electric arc, and progressively advancing said arc and member as t e welding proceeds, substantially as set forth. v

2. The method of arc-welding, which consists in placing an air-excluding memberover the metal to be welded, striking the arc therewith, observing the welding action of the arc, and advancing said arc and air-excluding member as the welding is accomplished, substantially 'as set forth.

3. The method of `arc-welding, which consists in positioning a portable'air-excluding cover about the arc, striking the arc with the metal to be welded, observing the welding action of the arc, and advancmg said arc and cover, as the welding operation proceeds, substantially as set forth.

4. The method of arc-welding, which consists in positioning a portable air-excluding cover of restricted interior capacity upon the metal to be welded, striking the arc therein, observingits progressive welding action, and advancing the arc and cover along the metal as the welding action progresses, substantially as set forth. p

In testimony whereof I do now alx my signature.

JOHN C. LINCOLN. 

